An electroconductive composite material includes a plurality of stacked prepregs. The prepreg is a carbon fiber woven fabric. For example, the electroconductive composite material may be a carbon fiber woven fabric impregnated with a thermosetting resin or a thermoplastic resin. In the prepreg, the carbon fibers in the resin are oriented in a predetermined direction. The arrangement disorder of the carbon fibers influences mechanical properties of the electroconductive composite material. Therefore, an arrangement state of the carbon fibers may be inspected in a manufacturing process of the electroconductive composite material.
When an electroconductive composite material has a form of flat plates, an arrangement disorder of the carbon fibers includes a disorder in a thickness direction (that is, out-of-plane direction) of the electroconductive composite material and a disorder in a direction perpendicular to the thickness direction (that is, in-plane direction). Therefore, in the manufacturing process of an electroconductive composite material, an arrangement disorder in the out-of-plane direction and an arrangement disorder in the in-plane direction are inspected for. For example, an ultrasonic flaw detection method described in Patent Literature 1 may be used for inspection for arrangement disorder in the out-of-plane direction. A method of cutting a flat plate-form electroconductive composite material and observing a cut surface thereof, or a method of finely cutting the electroconductive composite material and detecting the disorder in the carbon fibers using X-rays may be used for inspection for arrangement disorder in the in-plane direction. Further, for the inspection for arrangement disorder in the in-plane direction, for example, a fiber meandering detection method for the electroconductive composite material described in Patent Literature 2 may also be used.